This application seeks to use the natural antiphonal calling behavior of common marmosets to examine the neural mechanisms underlying vocal signal recognition in primates, focusing specifically on the role of prefrontal cortex in this process. Antiphonal calling occurs when one individual recognizes a species-specific long call and responds to that vocalization by producing the same type of vocalization. Because antiphonal calling requires that individuals recognize the initial vocalization, this behavior represents a natural recognition system that can be probed using the neuroethological approach. Specific Aim1 is to characterize the antiphonal calling response of marmosets in order to develop a behavioral assay for the subsequent components of the project. Specific Aim 2 is to use immediate early gene expression to determine the neural substrates underlying antiphonal calling. While auditory cortex is likely involved, which specific region of lateral prefrontal is involved in antiphonal calling is unknown. Specific Aim 3 is to record electrophysiological activity in prefrontal and auditory cortex to determine the functional role of these two cortical areas in call recognition. This project will form the foundation for a long term study of the neuroethology of primate communication and contribute to our understanding of complex sound processing in the primate neocortex.